Not too hasty to re-fuel the car (7)
I believe the answer is:
careful
'not too hasty to re-fuel' is the definition.
I can't tell whether this defines the answer.
'the car' is the wordplay.
I cannot really see how this works, but
'the car' could be 'car' and 'car' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for careful that I've seen before include "Diligent" , "Thrifty" , "Guarded" , "Thorough" , "Exercising caution" .)